Uncertainty in North America wet deposition isopleth maps: Effect of site selection and valid sample criteria

Abstract

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1987 wet deposition temporal and spatial patterns in North America

“…This selection depends on the representativeness of the site and the completeness of the data for the period of interest. Criteria for selection have been developed by the Unified Deposition Database Committee (Olsen et al 1990). When several maps based on the same time period of data are compared, a major reason for qualitative differences is the selection of different subsets of data by the researchers.…”

“…When several maps based on the same time period of data are compared, a major reason for qualitative differences is the selection of different subsets of data by the researchers. Simpson and Olsen (1990) completed a study on the effect of using different data completeness criteria on isopleth maps. They concluded that the overall general regional patterns are reasonably insensitive to changes in criteria but that local features can be highly sensitive.…”

“…Each network included in this report has and implements a quality assurance program. However, even with careful attention, some samples must be declared invalid because of the violation of some aspect of the protocol that affects the sample's representativeness of Network from 1979Network 197919811984 1979 1980 1981 1982 1983 1984 1985 1986 1987 Olsen et al (1990) and used in the ADS 1986 summary report by Sweeney and Olsen (1989).…”

“…Total wet deposition is the product of the precipitation-weighted mean concentration and the total precipitation, as determined by the rain gage, during the period. Olsen et al (1990) give additional details of the calculation procedures.…”

“…Although calculation of an annual, seasonal , or four-weekly summary based on valid data is possible for a site that operated during the summary period, this does not imply that sufficient val id data for the period are present to ensure a meaningful, i.e., representative, summary. The Unified Deposition Database Committee (UDDC) (Olsen et al 1990) The ADS 1986 data summary report by Sweeney and Olsen (1989) discusses the UDDC data completeness measures and criteria. Application of the UDDC criteria significantly reduces the number of sites available for defining the temporal or spatial pattern of wet deposition.…”